Powering vehicles with aluminum

Pop a few aluminum bits into this little RC racer and you’ll have power for around forty minutes. This concept, which has been patented, is the result of a college research project. It uses a chemical reaction between aqueous Sodium Hydroxide and aluminum. The result of that reaction is hydrogen, which is gathered and directed to a fuel cell that drives the car.

Novel? Yes. Interesting? Absolutely. But you should be raising an eyebrow at the dubious choice of fuel that is aluminum.

If you don’t know what we’re talking about let us paint you a picture. Aluminum is a metal that is refined from bauxite ore. It takes an immense amount of electricity to smelt the metal. This is usually justified because aluminum is one of the most recyclable substances on earth, capable of being melted down and reformed countless times. But dissolving it in drain cleaner breaks it down and then it’s gone. So what we have here simply must be the least efficient disposable battery so far developed. It’d probably use less resources to grow and harvest lemons as a power source.

So, this guy has done what has defied the greatest minds in the history of science: the destruction of matter. In this case he has made aluminum atoms disappear from the universe. Or has he converted them directly to energy? Probably not, since the damage caused by the release of that much energy would probably have been page 1, above the fold news in and of itself. Possibly, he has merely converted metallic Al into aluminum hydroxide, a feedstock for several industrial processes, thus readily recyclable/reusable. Please excuse the rending of flesh (sarcasm), couldn’t resist due to issues of poor character.

Fuel cells aren’t anything new either, Allis Chalmers made those back in the 50’s, please correct me if my year is wrong. Methods of making hydrogen keep coming, but letting your 8 year old handle a mixture of lye + water, this should be rated for kids 14+.

Critisism, on MY Hackaday?
It’s more likely to get respect from me than they think!

@Xiver
I do hope you’re being facetious.

@vmspionage
Not just a squirter full of lye, but when it’s running, a tank full of hydrogen too. A great way to teach children and parents respect for dangerouHAHAHAHA oh who am I kidding, they’d hurt themselves through sheer idiocy and sue for everything the inventor ever owned.

Mr. Szczys, did anyone ever tell you about conservation of mass? It “breaks down” and “is gone” when you mix it with NaOH? Um, this isn’t a nuclear reaction happening here!

The aluminum doesn’t disappear when you put it in the sodium hydroxide, it just turns into sodium aluminate and hydrogen. Only an idiot would then dump the NaAlO2. Instead, you collect the waste and send it for reprocessing into elemental aluminum. The energy to drive the car is ultimately coming from whatever process you’re using to refine or recycle the aluminum metal

They’ve been talking about this process as a portable method of generating hydrogen for years now, and no one has ever suggested that the reactants were disposable. They always include a process to recover the expended “battery” and reprocess the materials inside.

The aluminum is not destroyed. From what I remember, you can reverse the process. I don’t remember if you need chemical or physical reaction to reverse it though.

I had this idea for powering an off-grid house. Big ol’ chunk of aluminum in a container with lye in it, pour in some water, and you get hydrogen until the water has been off-gassed as hydrogen and the oxygen has been bonded to the aluminum.

Need more hydrogen gas? Add more water until the aluminum has been oxidized.

Seriously, the performance function for energy storage systems is extremely complex and time variant. There are many different types of devices that need energy storage, with the economic practicality affected by such factors as the costs of alternatives, physical size, device complexity/final cost, geopolitics (e.g., price of oil), etc. etc. An energy storage system could very well hit a particular sweet spot for some rare but vital device, without being feasible for large or mainstream uses.

What macw said! Unless there’s something nuclear going on the aluminum is merely being reduced, it hasn’t gone anywhere! The fact that this has been patented is utterly absurd. Of course electricity is produced when Aluminum is reduced, this isn’t even novel: I did the exact same with except with Zinc about two months ago for an American Institute of Chemical Engineers (AIChE) competition and we took second place in the southwestern regional competition (http://www.egr.uh.edu/news/0410/?e=chemecar University of Houston, go Cougars). This technology has been around for years, zinc being preferable because it’s more common and less toxic once reacted. The whole idea is ridiculous because you can’t recharge it and at the end you’ve got a whole bunch of lye on your hands with nasty reduced metals in it.

This is what I love about Hack A Day – A: Original posting sounds logical to me (unfamiliar with these types of fuel cells). B: Someone in the readership (macw, Charles Sadler) has specific knowledge of the processes involved and puts things into a different perspective. C: I learn something without exposing myself to dangerous chemicals! (OK, gratuitous but there had to be a “C”).

If you want a safer and more economical version, try iron and acetic acid (vinegar). It will still produce hydrogen, though at a much slower rate depending on concentration. This way the ultimate energy source is coal instead of electricity (which is still mostly from coal, but not nearly as efficient).

Acetic acid is renewable, and there are millions of tonnes of scrap iron sitting around rusting.

in the earler ‘lemon battery’ post you mentioned, is it not just the oxidation of the zinc metal in the electrode (by acid in the lemon) that provides the energy, rather than the lemon juice itself? so, ‘harvesting energy’ from lemons might not be feasable, as you would need to put the energy in first by reducing the zinc compounds found in ores to metallic zinc.

The problem is that recycling the alumina is less than 50% energy efficient, and the fuel cell is less than 50% efficient, and the power station that makes the electricity to reduce the alumina back to aluminium is less than 50% efficient…

You don’t make Hydrogen using electrolysis and freeze it or compress it. You extract it form the common chemicals and use it as it is being released by chemical reaction. That is the way to go, not the cryo-compressed hydrogen bomb under the hood. Simple, elegant, low tech, affordable, job killing.

Bravo. Now back to drawing table. The world needs to see the full scale model. And don’t forget to reprocess the waste product back in to the fuel.

C’mon Mike, read the article again! …”closes the cycle of aluminium, reducing pollution caused by its extraction, the use of aluminium is because it is a residual and when enters in contact with sodium hydroxide produces hydrogen and aluminium hydroxide and sodium hydroxide, which can be reused. The aluminium hydroxide can be converted in alumina throughout a calcination process. With the alumina, aluminium can be obtained, in this case is more pure than the aluminium is currently recycled, and the same purity which is extracted from opencast mines bauxite, which is very dangerous for the environment.”

“But you should be raising an eyebrow at the dubious choice of fuel that is aluminum.”
The article says he uses “aluminium soda ring cans” (or maybe soda can rings), which would likely end up in the landfill.

If I say I can hold my breath till I run out of oxygen, that does not mean I can hold my breath till the oxygen in my lung decays into some other element. It means I can hold my breath till the oxygen is converted to C02. Was the oxygen destroyed? Yes if we mean the molecule 02 and No if we mean the atom.

Considering mike said “But dissolving it in drain cleaner breaks it down and then it’s gone” it is obvious he was talking about the aluminium crystal not the individual atoms of aluminium. So all comments saying “The aluminium doesn’t disappear” etc.. indicate the commenter is really bad at getting context or has a bone to pick with HAD.

Some people are missing the point here. Metallic aluminium is created using an electrolytic process that involves an inordinate amount of electical energy. The energy retrieved from metallic aluminium by using sodium hydroxide to create hydrogen which is then used to create electricity which is then used to do mechanical work is small compared to the electrical energy that went into creating the metallic Al in the first place. This little car represents energy inefficiency on a grand scale. That’s what the fuss is about.

so, what’s to stop me from crushing up some bauxite to run my reactor, so i can recycle my spent fuel back into aluminum and whatever else is in bauxite, + my other reactants, minus the H and maybe some O’s if i’m lucky?
(besides my lack of a nearby bauxite mine)

There are so many things wrong with the article it’s scary. Clearly they have absolutely no idea how the chemical reaction works. The NaOH is not a catalyst, the given reaction is wrong, and they can’t even get their Back to the Future reference right.

This could turn into a very nice niche power supply, but it certainly has no application in real cars. It would be neat to see a mini combustion engine used with this instead of the fuel cell.

On a side note, with a bubbler to get all the water vapour out (it gets pretty hot and stuff) it’s great as a source of hydrogen for chemistry use and it makes a fine replacement for my broken propane torch with a syringe from an ink refill kit as tip.
Bit of hot glue and some soda bottles.
–Nathan

Although the article indicates this is a hydrolisis of aluminum as you stated this is a relatively slow reaction and I have a hard time believing they are getting a sizable amount of hydrogen that way. The article does not specifically state a mechanism but points towards the hydrolysis mechanism.

Instead I think this is much more likely a common aluminum-air battery (note the air in the chamber) as seen in the wikipedia page on the matter as well as many other sources: http://en.wikipedia.org/wiki/Aluminium_battery and the oxidation of aluminum provides energy.

If this were new or remarkable we would be hearing a lot more about efficient generation of hydrogen. As for “filling the gap” ordinary recycling is a much efficient process and this is in fact likely a monumental waste of energy, although trivial because it is done infrequently on a hobbyist basis.

Our version uses zinc instead of aluminum for safety. Zinc is safer than aluminum because the aluminum can become airborne in any high concentrations of lye which work best(NaOH works better than KOH). Aluminum does produce dramatically more power than Zinc, however it is consumed at much faster rate (seconds rather than minutes) and is more of a flash than a sustained process that would be ideal for most applications. We were producing at best 200mA at 1V (using very concentrated lye) per cell of Zinc electrodes which drops under load but is certainly enough to power a small dc motor, and presumably a receiver IC of some sort, particularly when connected in series/parallel.

This is very easy to reproduce on your own, the most difficult component to source being the lye (NaOH or KOH) which can often be found in liquid form as a certain brand of drain cleaning products, or at fertilizer stores. All you have to do is submerge your metal fuel (zinc electrodes are cheap at art supply stores for electroplating or online such as amazon for experiments, I do not recommend aluminum cans) in a bath of lye (connected with an alligator clip to one terminal of the motor) and to a piece of steel wool wrapped in a paper towel and a clip from the wool to the other motor terminal. With enough electrodes (current depends on surface area per Nerst equation) connected in series and in parallel the motor or RC car your fuel cell/battery is connected to will run.

here’s a question for the chem nerds: how do i get the aluminum back out of the sludge?

Nathan did some nice equations above, and the bayer process pretty much says cool it down to precipate out the aluminum hydroxide (white solid), then heating it to 1050 C to calcine it (maybe using that electric kiln from a few days ago http://hackaday.com/2011/04/13/building-an-electric-kiln/ ???)

can we stop here and have something we can reuse as fuel for another reaction (in the RC car)? or do we have to complete the process and smelt the alumina into aluminum? is there a better way that huge electrodes and a crapload of amps?

yes, it is so sad. worse still, people do similar in ‘real’ academic research that gets published in peer reviewed journals, there are loads of papers out there talking about such nonsense, even stuff using expensive metal complexes to catch CO2 emissions, to ‘save the planet’. just as long as it ticks the right boxes it will get published somewhere, and the professor will get their research grant. rant over.

@Edward: If you think the reaction is slow – try it. It’s also very exothermic and boils part of the water off.

On lye being difficult to source – *every* drain cleaner has it out here (Holland), except for the hippie ones with citric acid.

To those claiming it’s an aluminium-air battery, why would they need to bubble hydrogen through vinegar and dry it with silica?

On the zero CO2 part – I call bullshit.
As mentioned above, aluminium production takes loads of power and is quite inefficient.
However, even if this power is produced cleanly, there is another factor. The anodes used for Al production are carbon. At the anode, oxygen is formed. And we can all guess what we get when we combine heat, oxygen and carbon..

@Rachel As it cools down aluminium hydroxide precipitates because of solubility changes.

On another side note, they’re not the first ones to come up with this. Problem is, unless you use different anodes (and carbon isn’t the most conductive of suitable electrodes) and a better power source, such as nuclear power, it is *terribly* inefficient. Perhaps you could get efficiency up to 50%-ish.

Its not a battery cell, its a H2-powered motor, so they are using the reaction mentioned by Nathan Zadokis, not the one mentioned by Edward. If you get a look at the photos on the website, you can see a red box (batteries) at the back of the reaction tank. The vertical chamber with liquid on it, is actually a separation chamber, you dont want bubbles of water getting into the motor!